Two Fairfax County men were denied entry into Israel after authorities found a letter written in Arabic inside their carry-on bags that the FBI says was a farewell note in preparation for a suicide terrorist mission, according to a criminal complaint unsealed yesterday.

The men, Mohammed Osman Idris and Mohammed El-Yacoubi, U.S. citizens born and raised in Northern Virginia, turned up for their Dec. 13 flight from New York to Tel Aviv and drew suspicion, the FBI says in an affidavit. The young Muslim men had paid cash for their tickets and were carrying $2,000. They had no checked baggage, no hotel reservations and no stated itinerary. Their passports were only three days old. The letter, written by El-Yacoubi's brother, is about "Jihad" and "traveling to Allah."

Idris, an Annandale resident, was charged with lying to a grand jury about why he and El-Yacoubi, of Fairfax Station, had gotten the new passports. El-Yacoubi has not been charged with a crime, and both men deny criminal intentions.

The case puzzles government investigators, officials familiar with it said. Three months of intense investigation have turned up no hard ties to terrorists and little evidence beyond the letter and Idris's alleged lie, sources said. In addition, Idris, El-Yacoubi and his younger brother were born in this country and have strong ties to the Washington area. All three graduated from the Islamic Saudi Academy in Alexandria.

"What do you do in a case like this?" one government official said. "How can you not act?"

The U.S. attorney's office in Alexandria declined to comment. But prosecutors did not appeal a decision to release Idris on bond after his arrest. El-Yacoubi and his brother, Abdalmuhssin, a student at the University of Virginia, were jailed initially as material witnesses and later released.

Reached at home, Idris, 24, said: "I can't talk to you. . . . It's really not that big a deal." His attorney, Tom Walsh, did not return two phone calls seeking comment.

Mohammed El-Yacoubi, 23, said in an interview that he spent six weeks and one day in jail and $42,000 in lawyer fees over what he called a misunderstanding.

"Ninety-eight percent of the information they had was false and inaccurate," said El-Yacoubi, who graduated from George Mason University in August 2000. "Everything they relied on was found to be not true. My lawyer cleared everything up."

His attorney, Jefferson Gray, said his client "had no criminal purpose in making his trip to Israel and is not associated with any radical or terrorist group."

Patrick Anderson, Abdalmuhssin El-Yacoubi's lawyer, said his client "committed no crime, but he was locked in jail for two weeks because of the overreaching and overzealousness of a frightened Justice Department."

According to the criminal complaint filed against Idris, he and El-Yacoubi wanted new passports because their old ones had Saudi stamps that they feared would alienate Israeli authorities.

Idris is charged with lying to the grand jury for allegedly saying he lost his passport in January 2001, even though he told the passport office he discovered it on Dec. 4, 2001. Bank records show he used it to cash a check Dec. 5, the complaint says.

El-Yacoubi, whose father is of Palestinian heritage, said he was simply planning to celebrate the end of Ramadan in Jerusalem.

But FBI experts said the Arabic letter he was carrying had far more sinister connotations.

In it, according to the FBI translation, Abdalmuhssin wrote to his brother: "When I heard what you are going to carry out, my heart was filled with the feeling of grief and joy. . . . I have no right to prevent you from your migration to Allah and His holy messenger, but it is incumbent upon me to encourage you and help you, because Islam urges Jihad for the sake of Allah. . . . I hope that this letter will arrive before you travel to Allah and His messenger."

According to FBI experts, the language suggests that the elder El-Yacoubi was planning to commit some kind of terrorist attack. It "indicates that Mohammed El-Yacoubi was going to place himself at grave risk of injury or death for the sake of his Jihad," the complaint said.

But Mohammed El-Yacoubi said he didn't know why his brother worded the letter the way he did. "My brother's an overachiever. He writes that way," El-Yacoubi said.

He added, "They mistranslated the letter. 'Jihad' means 'struggle.' It's not fair that they did not translate that as 'struggle.' "

The younger El-Yacoubi did not respond to phone and e-mail messages seeking comment, and Anderson said he could not comment on why his client wrote the letter.

Staff writers Tom Jackman, Peter Whoriskey and Maria Glod contributed to this report.